302 



PART IV. CLASSIFICATION. 



The reproductive organs are of two kinds, compound and simple. 

 Of these the compound sporophore is universal, and is character- 

 istic of the sub-class ; it constitutes the fructification commonly 

 known as a Mushroom, a Toadstool, etc. The structure of this 

 fructification may be illustrated by reference to the common Mush- 

 room (Agaricus campestris). It consists of a stalk, termed the 



stipe, bearing at its 

 apex a large circu- 

 lar, somewhat um- 

 brella-shaped expan- 

 sion, the pileus. 

 On the underside of 

 the pileus are a 

 number of radiating 

 plates of tissue, the 

 lamella* (Fig. 183), 

 covered with the 

 spore-bearing layer 

 of cells, called the 

 hymenial layer or 

 hymenium. The 

 lamellae collectively 

 constitute the hy- 

 menophore. To- 

 wards the upper end 

 of the stipe is a 

 ring of tissue, the 

 annulus, the torn 

 remains of a mem- 

 brane (the velum) 

 which extended from 

 the stipe to the 

 margin of the pileus, 



FIG. 183. Agaticus campestris. A Tangential section of 

 the pileus, showing the lamellae (1) of the hymenophore. 

 B A similar section of a lamella more highly mag nifled 

 hy the hymenium; t the central tissue called the trarta. 

 C A portion of the same section more highly magnified 

 (x 650): q young basidia and paraphyses; ' the first 

 formation of spores on a basidium ; s" more advanced 

 stages ; at "" the spores have fallen off. (Alter Sachs.) 



enclosing the hy- 

 menial cavity (Fig. 

 182). 



The stipe consists 

 of a number of close- 

 ly-packed branching 

 hyphse, which, at its apex, spreads out to form the tissue of the 

 pileus. In the pileus the hyphse branch repeatedly, the hyphae 



